In the case of V-shaped combustion engines, the cylinders are arranged in two rows inclined toward one another. The pistons guided in the cylinders are respectively connected to a common crankshaft via a respective connecting rod; this crankshaft features several crankpins for the swivel mounting of the connecting rods. Here, the cylinders of the two rows are frequently offset toward one another in an axial direction such that the connecting rods of two approximately opposite cylinders are supported on two directly adjoining crankpins. Inasmuch as these crankpins feature longitudinal centre axes offset toward one another, a two-part crankpin (“split pin”) is formed, which is why corresponding crankshafts are designated as split-pin crankshafts.
Known deep rolling tools for deep-rolling the outside radii or recesses of split-pin crankshafts usually feature two separate housings in which work rollers are pivoted, that a rolling force is applied to and that are pressed into the radii or recesses of a split-pin crankpin. During machining the split-pin crankshaft rotates around its axis of rotation and the two housings follow—independently of one another—the respective lifting motions of the split-pin crankpins. Between the facing internal sides of the two housings there is located an additional assembly, functionally acting as a support device, which supports the two housings against one another. Such support is necessary as due to the rolling force being applied reaction forces are also generated that are transmitted from the work rollers to the housings and must be taken up.
From U.S. Pat. No. 5,575,167 A, a relevant support device is known, which consists of ring-shaped and flat bearing plates made of Teflon, nylon or other unspecified synthetic materials which primarily should feature good sliding characteristics and low wear.
In accordance with EP 0 661 137 B1 such a support device consists of a ring-shaped thrust bearing assembly located between the housings. This assembly effects an alignment of the two housings in parallel vertical planes, whilst these are rotated in relation to one another around the axis of a split-pin crankshaft or whilst a split-pin crankshaft rotates underneath the housings. For functionality it is essential that the thrust bearing assembly takes up and cancels out the resulting lateral pressure forces directed against one another, that are generated by the opposing work rollers inclined outwards during the rolling process. However, here problems may occur as the work rollers in axial direction of the crankshaft are fixed in end position by the crank webs limiting the radii or recesses. Thus, reaction forces can occur in the area of the housings located opposite to the crankshaft, which may cause a slight drifting apart of these areas and thereby have a detrimental effect on machining quality.
DE 103 57 441 B3 concerns a support for a hard-rolling roller head with two separate housings where the inner sides of the housings respectively feature an extension section which extends in rolling force direction to a point underneath the contact point between the work rollers and the radii or recesses to be deep-rolled. Here, the support device is embodied as a large surface support plate made of materials containing nylon, Teflon or carbon. The support plate is firmly connected to the inside and the extension sections of one of the two housings. This design has proven itself for providing and ensuring an effective support of the housings against one another and at the same time preventing the upper areas of the housings from drifting apart. However, a disadvantage here is that the two deep rolling head housings involved are in large surface contact with one another. As the housings—during a machining of split-pin crankshafts—carry out unusual movements that can be described exactly in part only (frequently these are similar to an ellipsis contour), they slide at the contact surfaces. Due to the work roller arrangement at an incline against one another, inside the two housings, they are pressed against one another by means of relatively high forces acting in axial crankshaft direction.